What Are Bellies in the Sewer Line? Causes, Risks, and Repair Solutions

Plumbing issues come in all shapes and sizes, but one of the more elusive problems homeowners face is a belly in the sewer line. If you’ve been told you have a "bellied pipe" or noticed frequent drain backups, this hidden issue could be the culprit.

Let’s break down what a sewer line belly is, why it happens, and the best solutions to fix it—without tearing up your yard.

What are Bellies?

A belly in the sewer line (also called a sag or low spot) occurs when a section of the underground pipe sinks due to shifting soil, poor installation, or ground settling. This dip in the pipeline causes wastewater and debris to collect in the sagging section rather than flowing smoothly to the main sewer.

Signs of a Bellied Sewer Line

If you suspect a pipe belly, look out for these common warning signs:

Frequent Drain Clogs – Solid waste accumulates in the belly, leading to slow drains and blockages. 

Gurgling Toilets & Fixtures – Air trapped in the pipes due to water pooling can create odd noises. 

Sewage Smells – Standing wastewater in the low spot can emit foul odors. 

Recurring Backups – If a plumber clears your drains, but the problem keeps returning, a pipe belly could be the underlying issue.

What Causes Bellies?

One of the most common causes of a sewer line belly is shifting soil. Over time, natural ground movement due to erosion, flooding, or the freeze-thaw cycle can cause pipes to settle unevenly. Without proper support, certain sections of the pipeline may sink, creating a low spot where water and waste accumulate.

Poor installation is another major contributor. When sewer lines are not installed with a solid, compacted bedding, they are more vulnerable to sagging under pressure. Insufficient bedding or improper backfilling techniques can leave pipes unsupported, allowing them to sink into the loose soil beneath.

Aging pipes are also a factor. Older sewer lines made from clay or cast iron can weaken over time, making them more prone to sagging. As pipes degrade, they lose structural integrity and may develop low spots, leading to drainage issues.

Lastly, heavy surface loads can contribute to pipe bellies. Driveways, patios, and even large trees placed above a sewer line can cause the ground beneath to shift, exerting pressure on the pipeline and increasing the likelihood of sagging.

Why are Bellies a Problem

A small sag might not seem like a big deal, but neglecting a bellied pipe can lead to serious plumbing issues over time.

A sewer line belly creates a stagnant section within the pipe where waste accumulates. Over time, this buildup leads to frequent blockages and backups, requiring constant maintenance and drain cleaning. Even if a plumber clears the blockage, the underlying issue remains, meaning the problem will continue to resurface.

Standing water in a sagging pipe can also cause internal pipe erosion. The constant presence of wastewater can weaken the pipe material, leading to cracks, leaks, or even pipe collapse. In severe cases, the sag can create a complete blockage, resulting in wastewater backing up into the home—a costly and unsanitary situation for any homeowner.

How to Fix a Bellied Sewer Line

The good news? There are solutions that fix sewer line bellies without major excavation.

1. Sewer Camera Inspection

The first step is a professional sewer camera inspection. This allows plumbers to pinpoint the exact location and severity of the belly before determining the best repair method.

2. Spot Repair Methods

Spot repairs are ideal for minor sewer line issues that are contained to a small area. These include small cracks, localized leaks, and minor blockages caused by tree roots or debris buildup. A professional plumber can determine whether a spot repair is a viable option after conducting a sewer camera inspection to assess the extent of the damage.

3. Traditional Pipe Replacement (Only When Necessary)

In some cases, a full excavation and pipe replacement may be required, especially if multiple sections of the sewer line have bellies or severe damage. This method is more invasive and requires digging up the affected section of the yard, but it may be the best option for pipes that are beyond repair.

Preventing Sewer Line Bellies

Regular maintenance and inspections can help homeowners avoid costly sewer line repairs. Scheduling a sewer camera inspection every few years allows professionals to catch potential sagging issues early before they escalate into major plumbing problems.

Monitoring the condition of your yard can also provide early warning signs of shifting soil. If you notice unexplained wet spots, sinkholes, or patches of overly lush grass, it could indicate an issue with your underground pipes. Addressing soil erosion and improving yard drainage can help prevent excessive ground movement that leads to bellies.

Another preventive measure is ensuring proper drainage around your home. Redirecting gutters and downspouts away from your foundation reduces the risk of soil shifting and pipe movement. If you're planning to install a driveway or heavy structure above a sewer line, consult a plumber to assess whether additional pipe reinforcement is needed.

Need Sewer Line Repair? We Can Help!

If you suspect a belly in your sewer line, Plumbing Today has top Omaha plumbing experts ready to assist your with all of your Omaha sewer line repair and replacement needs.

📞 Call us today at 402-581-9671 for professional sewer camera inspection and expert repair solutions!